The proposed study aims at elucidatting the time relationship between tissue cAMP, cGMP levels and acid secretion in isolated, intact frog gastric mucosa during stimulation or inhibition. The secretgogues are histamine and cholinergic agents and the inhibitor an H-2-antagonist, metiamide. The activation of cAMP- and cGMP-dependent protein kinases will be studied with the above mentioned secretagogues. The effect of the H-2-antagonist, metiamide, on cAMP- and cGMP-dependent protein kinases will be investigated during both resting and secreting conditions. The study will also try to establish the effect of phosphodiesterase inhibitors on cAMP and cGMP levels and the activation of resp. protein kinases.